clocksource/drivers/oxnas-rps: Fix irq_of_parse_and_map() return value

The irq_of_parse_and_map() returns 0 on failure, not a negative ERRNO.

Fixes: 8935527 ("clocksource/drivers/oxnas-rps: Add Oxford Semiconductor RPS Dual Timer")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220422104101.55754-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Author: krzk

drivers/clocksource/timer-oxnas-rps.c

@@ -236,7 +236,7 @@ static int __init oxnas_rps_timer_init(struct device_node *np)
 	}
 
 	rps->irq = irq_of_parse_and_map(np, 0);
-	if (rps->irq < 0) {
+	if (!rps->irq) {
 		ret = -EINVAL;
 		goto err_iomap;
 	}